Potholes and the like in roads need to be repaired, typically by filling with a mixture of gravel and liquid asphalt. When the asphalt hardens on cooling, a strong, composite material results for long term repair of the pothole.
In the prior art, Automated Road Repair Systems, Inc. has sold a vehicle which comprises a motor-driven, wheeled chassis upon which there is carried a gravel hopper, a tank for holding liquid asphalt, and a pump for providing air pressure. Hoses extend respectively from the gravel hopper and the asphalt tank along an extensible and retractable boom at the front of the vehicle, to meet at a mixing head at the end of the boom. The gravel hose is connected to the air pressure source, the gravel hopper has a bottom aperture which communicates with the hose for the gravel, with the flow of gravel being controlled by a vane-type feeder valve, which is constructed rather like a horizontal revolving door.
In order to allow the outer end of the gravel hose to move with the extensible and retractable boom, the hose is carried on the boom, with the central portion of the hose defining a loop, to provide adequate slack so that the outer end of the hose can extend with the extending boom.
Thus, the outer end of the boom, carrying the mixing head, can be adjusted by controlling of the boom so that it is positioned over the pothole. Then, typically, the repair area is blown clean with the high velocity air that can come through the gravel hose, while the vane-type feeder valve does not permit gravel to enter the gravel hose. Then, from the asphalt supply, asphalt without gravel enters the head and is blown into the hole for repair. Following this, a mixture of gravel and asphalt is applied with high pressure air to the repair area until the pothole is filled. Typically, no rolling or tamping is required because of the use of the high pressure air.
Thus, the vehicle can be operated by one man, replacing an entire crew, to drive along a road, locate damaged areas, and fill them up with the mixture of gravel and asphalt, to repair the pothole or large road crack without the driver ever leaving the control cab of the vehicle.
While the vehicle of the prior art has been highly useful and beneficial, it exhibits certain shortcomings and drawbacks which have increased its cost of operation and limited its use.
For example, the vane-type control valve positioned at the bottom of the gravel hopper has been found to exhibit rapid wear, in view of the strong compressed air flow conditions mixed with gravel encountered by the vane valve. The periodic replacement of such a vane valve has been expensive and time consuming.
Also, the gravel hose has exhibited rapid rates of wear, in part because the hitherto-necessary loop in the gravel hose causes the rapidly moving gravel under high air pressure to impact internal walls thereof all the way around the loop, which seriously increases the wear. Thus, the gravel hose must be replaced on a relatively frequent basis, which is an expensive proposition. Additionally, the non-straight configuration of the gravel hose can sometimes increase the possibility of the gravel plugging up in the hose in a curved section thereof, which is, of course, a significant problem which requires halting of repair operations with the vehicle.
Also, the hose for the asphalt must be of an excessive length so that it can move outwardly with the extending boom. Thus, when the boom is in retracted position, the asphalt hose forms undesired loops and the like which have the risk of becoming entangled with each other or with other parts of the vehicle. Particularly, the asphalt hose in the retracted-boom configuration sometimes has a tendency to touch the ground, with resulting serious wear as the vehicle travels.
In accordance with this invention, the above problems are solved, with the result that an efficiently operating machine is provided, with significantly better wear characteristics of the asphalt and gravel hoses and the bottom valve of the gravel hopper. Thus, the improved vehicle of this invention has significantly reduced maintenance costs and maintenance time.